Electrically conductive bus bars are frequently used to provide a common electrical connection between several terminal posts in an extended array of terminal posts, for example in the back plane of a telephone panel board in a main office. Conductive clips are either integrally formed with the bar or are provided as a separate part, each clip being formed to receive a terminal post to make electrical connection from the terminal post through the bus bar to the other terminal posts to be connected. Such bus bar systems are disclosed in U.S. Pat. Nos. 3,551,875; 3,582,864; 3,868,163; 3,918,778; 3,951,497; 3,985,414; and 4,029,377. In each of these systems the bus bar is conductive along its entire length and if it is desired to connect less than all of the terminal posts in a row together, portions of the bus bar must be separately insulated from the posts which are not to be connected as disclosed in U.S. Pat. Nos. 3,582,864 and 3,951,497. Thus, it is necessary with these prior art systems for the user to apply the insulation to appropriate portions of the bus bar, or the bus bar must be specially ordered for the customer's use. Often, both one of these alternatives are unacceptable.